A vortex generator typically consists of a small vane or flap that may be mounted on an aerodynamic surface to create a vortex in air flowing over the surface. Vortex generators may be used on many devices, but are used most commonly on the nacelles, fuselages, and aerodynamic wing surfaces of aircraft. When so placed on an aerodynamic surface, vortex generators delay flow separation and aerodynamic stalling, thereby improving the effectiveness of wings and control surfaces. In one particular application, vortex generators may be spaced along the front third of a wing surface in order to maintain steady airflow over the control surfaces at the trailing edge of the wing.
Vortex generators may be generally rectangular or triangular in shape and are mounted to extend substantially perpendicular to the surface on which they are mounted. Typically, vortex generators may be shaped to extend from the aerodynamic surface to about 80% as high as the boundary layer of air passing over the surface and extend span-wise near the thickest part of an aircraft wing. When mounted on an aircraft wing, vortex generators typically are positioned obliquely relative to the span of the wing so that they have an angle of attack with respect to local air flow.
Vortex generators typically are most needed during low speed, low-altitude flight, such as during take-off and landing. In other applications, they may be needed only during high-speed, high-altitude cruise. Since vortex generators typically are fixed vane devices, they remain deployed at all times during flight. This may result in unnecessary extra drag and resultant increase in fuel consumption.
In response to the negative effects of vortex generators during cruise, deployable vortex generators have been developed in which the aerodynamic surface or flap of the generator is deployed only during take-off, landing and other low speed operation, and is otherwise stowed and removed from exposure to air flow during cruise. Accordingly, there is a need for a vortex generator that may be actuated between stowed and deployed positions with a minimum of cost and structure.